Degrees of freedom region for an interference network with general message demands

Ke, Shaoying; Ramamoorthy,; Wang, Hong; Yin, Yin

doi:10.1109/isit.2011.6034148

Cited by 17 publications

(18 citation statements)

References 32 publications

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“…The concept of this signal space alignment has been successfully adapted to various network environments, e.g., see [10], [12]- [18] and the references therein. It was shown in [19], [20] that interference alignment can also be attained on fixed (not time-varying) interference channels.…”

Section: A Related Work 1) Degrees Of Freedommentioning

confidence: 99%

“…Figure 7 illustrates the channel space partitioning with respect to h i,j ∈ C. We can define Q 2 and A 2 (Q) for the second hop as the same manner in (18) and (19) by substituting A ∈ ∆(Z 2×2M + Z 2×2M ) and A ∈ C 2×2M , respectively. We will only use the first-hop channel instances in ∪ Q∈Q1 A 1 (Q) and the second-hop channel instances in ∪ Q∈Q2 A 2 (Q) for transmission.…”

Section: ) Partitioning and Pairing Of Channel Spacementioning

confidence: 99%

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Approximate Ergodic Capacity of a Class of Fading Two-User Two-Hop Networks

Jeon

Wang

Gastpar

2014

IEEE Trans. Inform. Theory

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We consider a fading AWGN 2-user 2-hop network where the channel coefficients are independent and identically distributed (i.i.d.) drawn from a continuous distribution and vary over time. For a broad class of channel distributions, we characterize the ergodic sum capacity to within a constant number of bits/sec/Hz, independent of signal-to-noise ratio. The achievability follows from the analysis of an interference neutralization scheme where the relays are partitioned into M pairs, and interference is neutralized separately by each pair of relays. When M = 1, the proposed ergodic interference neutralization characterizes the ergodic sum capacity to within 4 bits/sec/Hz for i.i.d. uniform phase fading and approximately 4.7 bits/sec/Hz for i.i.d. Rayleigh fading. We further show that this gap can be tightened to 4 log π − 4 bits/sec/Hz (approximately 2.6) for i.i.d. uniform phase fading and 4 − 4 log( Index TermsAmplify-and-forward, approximate capacity, ergodic capacity, fading, interference neutralization, two unicast, two-user two-hop networks.

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Section: A Related Work 1) Degrees Of Freedommentioning

confidence: 99%

Section: ) Partitioning and Pairing Of Channel Spacementioning

confidence: 99%

Approximate Ergodic Capacity of a Class of Fading Two-User Two-Hop Networks

Jeon

Wang

Gastpar

2014

IEEE Trans. Inform. Theory

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“…The concept of this signal space alignment has been successfully adapted to various network environments, e.g., see [11]- [13], [21]- [25] and the references therein. It was shown in [26], [27] that IA can also be attained on fixed (not time-varying) channel coefficients.…”

Section: B Previous Workmentioning

confidence: 99%

Degrees of freedom of uplink-downlink multiantenna cellular networks

Jeon

Suh

2014

2014 IEEE International Symposium on Information Theory

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An uplink-downlink two-cell cellular network is studied in which the first base station (BS) with M 1 antennas receives independent messages from its N 1 serving users, while the second BS with M 2 antennas transmits independent messages to its N 2 serving users. That is, the first and second cells operate as uplink and downlink, respectively. Each user is assumed to have a single antenna. Under this uplink-downlink setting, the sum degrees of freedom (DoF) is completely characterized as the minimum of, and max(N 1 , N 2 ), where a + denotes max(0, a). The result demonstrates that, for a broad class of network configurations, operating one of the two cells as uplink and the other cell as downlink can strictly improve the sum DoF compared to the conventional uplink or downlink operation, in which both cells operate as either uplink or downlink. The DoF gain from such uplink-downlink operation is further shown to be achievable for heterogeneous cellular networks having hotspots and with delayed channel state information.

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“…As it turns out, joint processing at one end, e.g., at the receivers in a SIMO X network, allows a larger space within which the desired signals can be resolved more efficiently from the interference. The use of the CJ scheme for achievability is significant because the same scheme often translates into the rational dimensions framework to establish corresponding DoF results in static settings (see, e.g., [3,12,13]). Indeed, the DoF results of this paper have been recently extended to constant settings by Zamanighomi and Wang in [14].…”

Section: Summary Of Contributionmentioning

confidence: 99%

Degrees of Freedom of MIMO $X$ Networks: Spatial Scale Invariance and One-Sided Decomposability

Sun

Gou

Jafar

2013

IEEE Trans. Inform. Theory

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We show that an M × N user MIMO X network with A antennas at each node has A M N M +N −1 degrees of freedom (DoF), thus resolving in this case a discrepancy between the spatial scale invariance conjecture (scaling the number of antennas at each node by a constant factor will scale the total DoF by the same factor) and a decomposability property of overconstrained wireless networks. While the best previously-known general DoF outer bound is consistent with the spatial invariance conjecture, the best previously-known general DoF inner bound, inspired by the K user MIMO interference channel, was based on the decomposition of every transmitter and receiver into multiple single antenna nodes, transforming the network into an AM × AN user SISO X network. While such a decomposition is DoF optimal for the K user MIMO interference channel, a gap remained between the best inner and outer bound for the MIMO X channel. Here we close this gap with the new insight that the MIMO X network is only one-sided decomposable, i.e., either all the transmitters or all the receivers (but not both) can be decomposed by splitting multiple antenna nodes into multiple single antenna nodes without loss of DoF. The result is extended to SIMO and MISO X networks as well and in each case the DoF results satisfy the spatial scale invariance property. In addition, the feasibility of linear interference alignment is investigated based only on spatial beamforming without symbol extensions. Similar to MIMO interference networks, we show that when the problem is improper, it is infeasible.

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Degrees of freedom region for an interference network with general message demands

Cited by 17 publications

References 32 publications

Approximate Ergodic Capacity of a Class of Fading Two-User Two-Hop Networks

Approximate Ergodic Capacity of a Class of Fading Two-User Two-Hop Networks

Degrees of freedom of uplink-downlink multiantenna cellular networks

Degrees of Freedom of MIMO $X$ Networks: Spatial Scale Invariance and One-Sided Decomposability

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